Cerebrovascular disease includes any abnormality of the brain resulting from a pathologic process of a blood vessel. A pathologic process of a blood vessel includes any one or more of the following: an occlusion of a blood vessel lumen by thrombus or embolus, a rupture of a blood vessel, an altered permeability of a blood-vessel wall, and increased viscosity or other change in the quality of blood.
Cerebrovascular disease is typically readily diagnosable because of how it manifests. Cerebrovascular disease typically manifests as a stroke. A stroke can be characterized as a sudden nonconvulsive, focal neurologic deficit. That is, stroke can be characterized as the death of brain tissue that results from lack of blood flow and insufficient oxygen to the brain. After heart disease and cancer, stroke is the leading cause of death in the United States. In the United States, there are approximately 500,000 cases of stroke annually. And these 500,000 cases give rise to about 175,000 fatalities.
A stroke can be ischemic or hemorrhagic. In an ischemic stroke, the blood supply to part of the brain is reduced or terminated either by a blood clot that blocks a blood vessel or by atherosclerosis. Reducing or terminating blood flow to the brain is known as cerebral ischemia. Cerebral ischemia can last for seconds to minutes, and when cerebral ischemia occurs for more than a few minutes, infarction of brain tissue results. A blood vessel can be blocked by a blood clot that arises from thrombus or embolus. Yet cerebral ischemia can also arise from the failure of circulation and hypotension from severe and prolonged cardiac decompensation or shock.
In a hemorrhagic stroke, the brain is damaged by a blood vessel bursting, which prevents normal blood flow and allows blood to leak into an area of the brain. In some instances, the blood leaks from a small artery. When blood leaks into the brain, a hematoma is formed in the brain and blood can spread into ventricles and subarachnoid space.
In cerebral hemorrhage, blood leaks from the vessel (usually a small artery) directly into the brain forming a hematoma, and the blood spreads into the ventricles and subarachnoid space. The hematoma can cause physical disruption of the brain tissue and pressure on the surrounding brain areas. When the blood leakage stops, the hematoma can slowly disintegrate and be absorbed over a period of weeks and months.
Several factors, including hypertension, heart disease, atrial fibrillation, diabetes mellitus, cigarette smoking of long duration, hyperlipidemia, use of birth control pills, and systemic diseases associated with a hypercoagulable state, are known to increase the susceptibility of individuals to stroke.
It is desirable to develop treatments for cerebrovascular disease, including cerebral hemorrhage, cerebral ischemia, ischemic stroke, hemorrhagic stroke, and ischemic reperfusion injury arising from reintroduction of blood flow following cerebral ischemia or ischemic stroke.